A recurring problem that is evident in a variety of technologies is that of storing information so that it requires the least possible amount of resources. This information may be in the form of computer data, words, pictures or information presented in other formats, and may be converted from one type of data to another in the storage process. One application of particular importance is the ability to store data that can be used to positively identify a person, as part of a security system. The information that needs to be stored for that purpose includes photographs, fingerprints, signatures and any other data that can establish a person's identity.
The success of many systems using large amounts of stored information often lies in the ability to compress the data representing that information, so that it is made available in an inexpensive manner anywhere it is needed. In the case of identification systems, it is useful to incorporate in identification cards sufficient information to positively identify a person. The data should also be in a format that cannot be easily forged or altered. At the same time, the information cannot occupy an excessive amount of storage, computer memory or physical space, depending on its format, since that translates in additional cost or size of the identification device. More generally, any system using large amounts of data benefits from storing that data in a more efficient and inexpensive manner.
In many systems that access data in a decentralized manner, such as in systems used for the identification of persons, an additional requirement is that all necessary data be accessible without having to connect to a data base, computer network, or other central information system. Sufficient information has to be stored at the remote locations so it may be reviewed without connecting to a communications system. To store the additional data efficiently, sophisticated compression methods must be used, to fit as much data as possible in a restricted storage, or to minimize the storage required. In particular, images of a person's face may have to be stored for identification purposes, but photographs generally require a large amount of storage to be saved. Improved compression methods may increase the usefulness of identification methods that use facial recognition to identify a subject.